God has given us His inspired Word, the Bible. The word "perfect" means to be complete. Paul places further emphasis on this thought by saying that the man of God is "throughly furnished" meaning completely equipped. Thus God's word (the Bible) says that we can be completely outfitted, lacking in nothing as it pertains to God's will.
All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness: That the man of God may be perfect, thoroughly furnished unto all good works.